Claims:1. A circuit breaker comprising:
a fixed contact (1);
a moving contact (2);
a shaft (6) comprising a compression spring (13) and a leaf spring (8), wherein the compression spring (13) and the leaf spring (8) provide contact force required to maintain pressure between the moving contact (2) and the fixed contact (1) to a desired level.

2. The circuit breaker of claim 1, wherein the circuit breaker further comprises a flexible conductor (3), and a conductor fixing block (4) that connects the moving contact (2) with a terminal contact (5).

3. The circuit breaker of claim 1, wherein the leaf spring (8) is arranged in cantilever manner to aid the movable contact (2) after a defined level of opening.

4. The circuit breaker of claim 1, wherein the leaf spring (8) provides force on the movable contact (2) through roller (9) that is hinged at one end of the moving contact (2) by means of a roller pin (10).

5. The circuit breaker of claim 1, wherein during short circuit condition, an electromagnetic force acts between the moving contact (2) and the fixed contact (1), which force rotates the moving contact (2) away from the fixed contact (1) and brings it to repelled position.
6. The circuit breaker of claim 5, wherein during repelled position, the leaf spring (8) torque on the moving contact (2) aids in opening, and wherein the compression spring (13) provides reduction in torque after a defined level of opening of the moving contact (2).

7. The circuit breaker of claim 1, wherein a metallic pin (11) is used for holding the moving contact (2) with the shaft (6).
8. The circuit breaker of claim 1, wherein the moving contact (2) is covered by an insulating cover (15).

9. The circuit breaker of claim 1, wherein the compression spring (13) is associated with a metallic slider (14), wherein the compression spring (13) is connected between the moving contact (2) at one end and a shaft (6) cavity at the other end using the metallic slider (14).

10. The circuit breaker of claim 1, wherein the shaft (6) comprises a plurality of cavities to hold corresponding one or more movable contacts for each pole.

11. The circuit breaker of claim 1, wherein the movable contact (2) has a circular profile with a center around its movable axis.
, Description:TECHNICAL FIELD
[0001] The present disclosure relates generally to circuit breakers, and particularly to an improved contact system for circuit breakers.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Electrical switching apparatus, such as circuit breakers, provide protection for electrical systems from electrical fault conditions such as, for example, current overloads, short circuits, abnormal voltage and other fault conditions. Typically, circuit breakers include an operating mechanism which opens electrical contact assemblies to interrupt the flow of current trough the conductors of an electrical system in response to such fault conditions.
[0004] Many low-voltage circuit breakers, for example, employ a molded housing having two parts, a first half or front part (e.g., a molded cover), and a second half or rear part (e.g., a molded base). The operating mechanism for such circuit breakers is often mounted to the front part of the housing, and typically includes an operating handle and/or button(s) which, at one end, is (are) accessible from the exterior of the molded housing and, at the other end, is (are) coupled to a pivotable pole shaft. Electrical contact assemblies, which are also disposed within the molded housing, generally comprise a conductor assembly including a movable contact assembly having a plurality of movable contacts, and a stationary contact assembly having a plurality of corresponding stationary contacts. The movable contact assembly is electrically connected to a generally rigid conductor of the conductor assembly by flexible conductors,. The movable contact assembly includes a plurality of movable contact arms or fingers, each carrying one of the movable contacts and being pivotably coupled to a contact arm carrier. The contact arm carrier is pivoted by a protrusion or arm on the pole shaft of the circuit breaker operating mechanism to move the movable contacts into and out of electrical contact with the corresponding stationary contacts of the stationary contact assembly. The contact arm carrier includes a contact spring assembly structured to bias the fingers of the movable contact assembly against the stationary contacts of the stationary contact assembly in order to provide and maintain contact pressure when the circuit breaker is closed, and to accommodate wear.
[0005] Shaft construction enables the design of single break arrangement that helps in make and break of electrical contacts (Stationary and Fixed) under normal and abnormal conditions. Shaft of the circuit breaker has to be robust as high-electro dynamic repulsive forces are generated between the stationary and moving contacts in the over current conditions and for enabling the multiple switching operations. However, non-reducing repel torque on the movable contact can affect the breaking capacity. Furthermore, in existing contact systems, contact pressure reduces after contact button erosion, leading to increased temperature rise.
[0006] There is therefore a need in the art for an improved contact system for a circuit breaker.
[0007] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0008] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0009] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0010] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0011] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

OBJECTS OF THE INVENTION
[0012] It is an object of the present disclosure to provide an improved contact system for a circuit breaker.
[0013] It is an object of the present disclosure to provide an improved contact system that enables increase in contact pressure without sacrificing stress limit of the spring as change in deflection of the spring is reduced.
[0014] It is an object of the present disclosure to provide an improved contact system that enables contact pressure to remain constant even after erosion of buttons.
[0015] It is an object of the present disclosure to provide an improved contact system having two springs that enables speed of the moving contact to be increased during repulsion as one spring has reducing torque and the other spring has negative torque on moving contact repel opening.
[0016] It is an object of the present disclosure to provide an improved contact system that has rollers configured between the movable contact and a leaf spring that is used to reduce frictional torque.

SUMMARY
[0017] The present disclosure relates generally to circuit breakers, and particularly to an improved contact system for circuit breakers. The present disclosure further relates to the field of protection devices, particularly circuit breakers, involving a novel embodiment to enhance the performance in normal operation and at breaking capacity. In another aspect, the present disclosure relates to switching devices such as circuit breakers that typically have at least one solid stationary electrical contact coupled/uncoupled to a solid moving electrical contact, which provides a path to carry or interrupt the electrical current in the network.
[0018] In an aspect, the present disclosure relates to a circuit breaker that includes a fixed contact, a moving contact, and a shaft comprising a compression spring and a leaf spring, wherein the compression spring and the leaf spring provide contact force required to maintain pressure between the moving contact and the fixed contact to a desired level.
[0019] In another aspect, the circuit breaker can further include a flexible conductor, and a conductor fixing block that connects the moving contact with a terminal contact. In yet another aspect, the leaf spring is arranged in cantilever manner to aid the movable contact after a defined level of opening. In another aspect, the leaf spring can provide force on the movable contact through roller that is hinged at one end of the moving contact by means of a roller pin.
[0020] In another aspect, during short circuit condition, an electromagnetic force acts between the moving contact and the fixed contact, which force rotates the moving contact away from the fixed contact and brings it to repelled position. In an aspect, during repelled position, the leaf spring torque on the moving contact aids in opening, and wherein the compression spring provides reduction in torque after a defined level of opening of the moving contact. In an aspect, a metallic pin can be used for holding the moving contact with the shaft.
[0021] In another aspect, the moving contact can be covered by an insulating cover. Furthermore, the compression spring can be associated with a metallic slider, wherein the compression spring can be connected between the moving contact at one end and a shaft cavity at the other end using the metallic slider. In an aspect, the shaft can include a plurality of cavities to hold corresponding one or more movable contacts for each pole. In an aspect, the movable contact has a circular profile with a center around its movable axis.
[0022] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components

BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0024] FIG. 1 illustrates a cross-section view of the proposed circuit breaker contact system with shaft assembly in ‘ON’ condition in accordance with an embodiment of the present disclosure.
[0025] FIG. 2 illustrates a cross-section view of the proposed shaft assembly having moving contact arrangement with the compression and the leaf springs in repel condition in accordance with an embodiment of the present disclosure.
[0026] FIG. 3 illustrates a representation showing leaf spring shape and profile in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0027] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0028] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0029] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0030] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0031] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0032] The present disclosure relates generally to circuit breakers, and particularly to an improved contact system for circuit breakers. The present disclosure further relates to the field of protection devices, particularly circuit breakers, involving a novel embodiment to enhance the performance in normal operation and at breaking capacity. In another aspect, the present disclosure relates to switching devices such as circuit breakers that typically have at least one solid stationary electrical contact coupled/uncoupled to a solid moving electrical contact, which provides a path to carry or interrupt the electrical current in the network.
[0033] In an aspect, the present disclosure relates to a circuit breaker that includes a fixed contact, a moving contact, and a shaft comprising a compression spring and a leaf spring, wherein the compression spring and the leaf spring provide contact force required to maintain pressure between the moving contact and the fixed contact to a desired level.
[0034] In another aspect, the circuit breaker can further include a flexible conductor, and a conductor fixing block that connects the moving contact with a terminal contact. In yet another aspect, the leaf spring is arranged in cantilever manner to aid the movable contact after a defined level of opening. In another aspect, the leaf spring can provide force on the movable contact through roller that is hinged at one end of the moving contact by means of a roller pin.
[0035] In another aspect, during short circuit condition, an electromagnetic force acts between the moving contact and the fixed contact, which force rotates the moving contact away from the fixed contact and brings it to repelled position. In an aspect, during repelled position, the leaf spring torque on the moving contact aids in opening, and wherein the compression spring provides reduction in torque after a defined level of opening of the moving contact. In an aspect, a metallic pin can be used for holding the moving contact with the shaft.
[0036] In another aspect, the moving contact can be covered by an insulating cover. Furthermore, the compression spring can be associated with a metallic slider, wherein the compression spring can be connected between the moving contact at one end and a shaft cavity at the other end using the metallic slider. In an aspect, the shaft can include a plurality of cavities to hold corresponding one or more movable contacts for each pole. In an aspect, the movable contact has a circular profile with a center around its movable axis.
[0037] In an aspect, the present disclosure describes a robust shaft construction to provide multiple switching operations at the same time, ensuring desired contact pressure, frictionless rotation about its axis, high opening speed of electrical moving contact, and gas sealing of shaft from high pressure ionized gases ensuring healthiness of electrical part used for connecting electrical contact with outgoing terminal and avoidance of globules entrapment between movable contact and shaft. In the proposed disclosure, shaft and housings can have a special shape geometry that avoids shaft blockage because of globules insertion during heavy fault.
[0038] In an aspect, leaf and compression spring are used in the proposed design for providing contact pressure between the stationary electrical contact and moving contact. One end of the compression spring can rest on the shaft, and the other end can rest on the movable electrical contact with the help of a rectangular link to avoid buckling.
[0039] The leaf spring can be used as cantilever type, wherein one end of the leaf spring can be fixed with the shaft, and the other end can be used to provide contact pressure to the electrical moving contact. Roller or bearing can be used between movable contact and leaf spring to reduce friction during relative movement between movable contact and shaft. Leaf springs can be arranged in such a manner that during opening of electrical contacts at higher fault, it aids opening of movable contact.
[0040] In an aspect, the proposed disclosure uses elastic (leaf spring) spring in combination with compression spring so as to provide contact pressure by the movable contact to the fixed contact. Leaf spring torque direction reverses during short circuit repel opening, thus aiding in arc-quenching during short circuit. The proposed arrangement of compression and leaf spring provides contact pressure between the fixed and the movable contact, and torque on the movable contact decreases as the movable contact opens up during repel opening at short circuit faults.
[0041] With respect to FIG. 1, a cross section view of the proposed Circuit Breaker in ON condition is shown. The current conducts through fixed electrical contact 1 and the moving electrical contact 2, electrical flexible conductor 3, and flexible conductor fixing block 4 connecting the moving contact 2 to the terminal contact 5 and vice versa.
[0042] In an aspect, the compression spring 13 and leaf spring 8 are arranged inside the shaft 6 so as to provide contact force that is required to maintain pressure between the moving contact 2 and the fixed contact 1 to desired levels. The leaf spring 8 can be arranged in cantilever manner so as to aid the movable contact 2 after some level of opening, wherein the leaf spring 8 provides force on the movable contact 2 through roller 9. In an aspect, profile of the leaf spring 8 can be designed to give torque on the movable contact 2 to aid contact pressure between the fixed contact 1 and the movable contact 2, and enable the torque direction on the movable contact 2 to reverse after certain degree of rotation, which helps in giving high contact pressure during ON condition, constant pressure after erosion of buttons, and zero or reverse torque during repulsion of the moving contact 2. The leaf spring 8 can be made in such way that it can give contact pressure to multiple movable contact(s) 2 independently. This type of electrical contact arrangement helps augment short circuit breaking capacity of circuit breaker by increasing repel opening speed of the moving contact 2 through reduction of overall effective torque on the moving contact(s) 2.
[0043] In an aspect, the contacts can be designed in such a way that during short circuit conditions, an electromagnetic force acts between the electrical moving 2 and the fixed contacts 1, which force rotates the moving contact 2 away from fixed conductor/contact 1 and brings it to repelled position as shown in FIG. 2. During repelled condition, leaf spring 8 torque on the movable contact 2 aids opening, and compression spring 13 provides reduction in torque after some level of opening of the moving contact 2, giving the circuit breaker an ability to clear very high fault.
[0044] In an aspect, one purpose of the present disclosure is to develop robust shaft assembly that can enhance breaking capacity by opening the movable contact fast, and with reduced friction. It can effectively carry out ON, OFF, and TRIPPING operations before and after the short circuit. Furthermore, temperature rise post short circuit is under control.
[0045] The proposed disclosure therefore provides a new shaft assembly that can be used in circuit breakers, wherein an inventive arrangement of springs has been provided for providing torque to the movable contact 2. Furthermore, use of leaf spring 8 and roller\bearing 9 help in fast opening of the movable contact 2, whereas use of cantilever leaf spring 8 provides high contact pressure. Furthermore, shape of the leaf spring 8 provides contact pressure to multi-figure contact system.
[0046] In an aspect, with respect to FIGs. 1-3, the proposed shaft assembly includes a movable contact sub-assembly and a rotating/metallic pin 11 that is used for holding the movable contact sub-assembly in a shaft slot that is configured in the shaft 6. Movable contact sub-assembly can further include a moving contact 2 with an insulating cover 15 over it. Each of the FIGs. 1-3 shows an independent metallic roller 9 that is hinged at one side of the movable contacts 2.
[0047] In an aspect, one or more moving contacts 2 can be configured and connected with a flexible conductor 3 and then with an electrical conducting terminal 4, wherein two or more movable contacts 2 can be stacked for each pole. The movable contact sub-assembly, when assembled with the shaft 6, as shown in FIGs. 1 and 2, rotates across the rotating pin 11.
[0048] In an aspect, the movable contact sub-assembly can be assembled with the shaft 6, and be attached with a metallic link 14 that is configured inside a compression spring 13, which rests on the movable contact 2 on one end, and rests on the shafts’ 6 inner surface on the other end as shown in FIG. 2. In an aspect, torque on the moving contact 2 is reduced by the compression spring 13 as it rotates away from the fixed contact 1.
[0049] In an aspect, leaf spring 8 can be attached to the shaft 6, wherein a metallic/rotating link/roller 9 transfers the torque to the moving contact 2, and wherein the torque direction changes as it open by certain angle. The metallic roller 9 can be hinged on the moving contact 2 by the metallic pin 10 on the movable contact 2.
[0050] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0051] The present disclosure provides an improved contact system for a circuit breaker.
[0052] The present disclosure provides an improved contact system that enables increase in contact pressure without sacrificing stress limit of the spring as change in deflection of the spring is reduced.
[0053] The present disclosure provides an improved contact system that enables contact pressure to remain constant even after erosion of buttons.
[0054] The present disclosure provides an improved contact system having two springs that enables speed of the moving contact to be increased during repulsion as one spring has reducing torque and the other spring has negative torque on moving contact repel opening.
[0055] The present disclosure provides an improved contact system that has rollers configured between the movable contact and a leaf spring that is used to reduce frictional torque.